The invention relates to a luminaire having a concave reflector with an axis of symmetry and a circumferential edge transverse to said axis which bounds a light emanating aperture. The reflector comprises elongate facets which extend from the light emanating aperture towards the reflector axis of symmetry.
A lamp holder is accommodated on the axis of symmetry opposite to the light emanating aperture of the reflector. The lamp holder receives an electric lamp which has an elongate light source and secures the lamp with light source extending substantially axially in the reflector.
Such a luminaire is known from GB 523 215-B. The reflector of the said luminaire has facets whch are also concave transversely to their longitudinal direction. At the level of the light source the reflector has a circumferential bend. The reflector forms a light beam which illuminates a radiated object uniformly. However, the beam is rather narrow so that comparatively large objects cannot be illuminated with one luminaire and neither can comparatively small objects which are present at a comparatively small distance from the luminaire. In order to avoid this drawback the known luminaire would have to be made too bulky to be useful for practical purposes.
Another drawback of the known luminaire is that it also radiates light at comparatively large angles with the axis, which light does not contribute to the light flux of the beam but does betray the place where the luminaire is accommodated.
U.S. Application Ser. No. 128,757 filed Dec. 4, 1987, now U.S. Pat. No. 4,855,886, discloses a bowl-shaped reflector having a plurality of elongate facets which are parabolically curved in the direction of the focal axis but which have a cross-section which is straight. This reflector provides a broader beam for illuminating objects than the reflector disclosed in GB 523 215-B but does not provide a beam as sharply bounded as desired.